[PyQt] PyQt5 NULL QVariant

[Phil Thompson]

On 15 May 2016, at 7:06 am, Matthias Kuhn <matthias at opengis.ch> wrote:
> 
> On 14/05/16 20:22, Phil Thompson wrote:
>> On 11 May 2016, at 1:21 pm, Matthias Kuhn <matthias at opengis.ch> wrote:
>>> I just found the great pyqt5_register_from_qvariant_convertor API and it
>>> seems to work. So I guess we can even make this compatible with older
>>> versions and without upstream changes.
>>> Do you see any drawbacks from such an approach?
>> It depends - I don't know anything about OpenGIS or what part Python plays.
>> 
>> Your appproach will change behaviour of PyQt. If your application is a closed system, ie. it's not used with external code or user written code then that probably doesn't matter.
>> However if your code is an extension module that is used as part of the user's application then it is a really bad idea. Their code will behave in one way before your module is imported, and a different way afterwards.
> QGIS is two things, a desktop application for which python plugins can
> be written and a library which can be used in standalone applications.
> 
> The requirement to `import qgis` first applied already with PyQt4 to set
> the sip api version, so all code should already be prepared for this.
> The requirement is already a bit relaxed actually because now the import
> does no longer strictly need to happen before any PyQt imports.
> 
> I will be happy to lift this requirement, feel free to integrate my code
> directly in PyQt.

If you are already able to get away with imposing those restrictions then I'm not going to introduce an incompatibility for everybody else.

Phil